Methods for directed irradiation synthesis with ion and thermal beams

ABSTRACT

A method for fabricating structures includes on a substrate includes providing the substrate having a substrate surface, and generating nanostructures or microstructures on the substrate surface at least in part by exposing the substrate surface to thermal particles from a thermal particle source while irradiating the substrate surface with an ion beam. The generated nanostructures or microstructures have a smaller surface area than the area of incidence of the ion beam or a beam generated by the thermal particle source. The method also includes obtaining a measurement of a characteristic of the substrate surface and adjusting at least one of the thermal particle source and the ion beam based on the measurement.

This application is a continuation of U.S. patent application Ser. No.16/426,961, filed May 30, 2019, which is a continuation of U.S. patentapplication Ser. No. 15/924,026, filed Mar. 16, 2018, which is acontinuation of U.S. patent application Ser. No. 14/441,140, filed May6, 2015, which is a National Phase of International Application no.PCT/US2013/068819, filed Nov. 6, 2013, which in turn claims the benefitof priority of U.S. provisional application Ser. No. 61/723,039, filedNov. 6, 2012, the disclosures of all of which are incorporated byreference herein in their entirety.

TECHNICAL FIELD

The present disclosure is related to high-volume nanomanufacturingmulti-functional nano- and micro-scale structures with applications inenergy, catalysis, nanophotonics, nanoelectronics, surface engineeringand biomaterials, and particularly related to a process, process toolingand nano and micro-scale multi-functional structures synthesized withsequenced, asymmetric ion and thermal beams.

BACKGROUND

Ion beams can be used to induce patterned structures and uniquetopography at the nanoscale by means of sputtering and othersurface-related processes. This approach can have significantimplications to the design of nanostructured surfaces used for cellengineering and cell biology.

Irradiation-driven systems have been explored in similar moderate energyregimes dominated by knock-on atom displacement regimes forsemiconductor metallization microstructure control, artificial texturingof ceramics, engineering of nanostructured carbon, and compositionalpatterning of immiscible alloys. Such findings suggest thatirradiation-driven self-organized structures can have critical effectson surface properties of low dimensional state structures.

However, irradiation-driven systems have been limited to the study ofdissipative systems leading to permanent damage by operating in energyand flux regimes that limit self-organization of low-dimensional statestructures. Despite the use of low-energy ion-beams, there remaindifficulties with control of short and long-range ordering, surfacechemistry and topographical control. In addition, despite numerousexperiments and models that have investigated ioninduced surfacenanopatterning; synthesis design for ion-induced biomaterialsfunctionalization remains absent. Ion-induced strategies are only usedfor biocompatibility enhancement. One important limitation in currentnanomanufacturing is its dependence on naturally self-ordered processesthat balance kinetic and thermodynamic dissipative forces in the absenceof irradiation techniques. This dependence leads to limited control ofsurface chemistry and functionalization. Furthermore top-bottom andbottom-up surface patterning is predominantly dependent on focused beamtechnology. One example is the use of electron and ion-beamnanolithography, which pose an order-of-magnitude limitations towardshigh-volume manufacturing.

Therefore, there is a need for a novel process that removes theaforementioned limitations toward high-volume manufacturing and which isscalable.

SUMMARY OF THE INVENTION

The present disclosure provides a novel process and arrangement togenerate patterned structures and unique topography at the nanoscalewhile eliminating the shortcomings of the prior approaches related tohigh-volume manufacturing resulting in a process that is scalable to byvirtue of its intrinsic large-area simultaneous exposure of materialssurfaces and interfaces.

In a first embodiment, a method for fabricating structures includes on asubstrate includes providing the substrate having a substrate surface,and generating nanostructures or microstructures on the substratesurface at least in part by exposing the substrate surface to thermalparticles from a thermal particle source while irradiating the substratesurface with an ion beam. The generated nanostructures ormicrostructures have a smaller surface area than the area of incidenceof the ion beam or a beam generated by the thermal particle source. Themethod also includes obtaining a measurement of a characteristic of thesubstrate surface and adjusting at least one of the thermal particlesource and the ion beam based on the measurement.

The above-described features and advantages, as well as others, willbecome more readily apparent to those of ordinary skill in the art byreference to the following detailed description and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic of the components used to carry out exemplaryDIS processes according to an exemplary embodiment of the invention;

FIG. 2 shows a flow diagram of an exemplary embodiment of a DIS processthat may be carried out by the components of FIG. 1 .

FIG. 3 shows a schematic of exemplary microstructures generated on asubstrate surface in accordance with an embodiment of the invention;

FIG. 4 shows a graph of computational simulations illustrating changesin surface composition as a function of controlling the ratio of fluxesbetween thermal and energetic particles of an exemplary metal;

FIG. 5 shows a schematic of the DIS synthesis process for energetic,thermal and combined energetic-thermal metal beams on a transition-metalthin-film;

FIG. 6 shows a graph of exemplary in-situ data for DIS-generated surfacepatterns that influence the optical EUV reflectivity of a system;

FIG. 7 shows a schematic diagram of an exemplary embodiment of a systemthat includes the components of FIG. 1 as well as devices for monitoringand controlling the process;

FIG. 8 shows a schematic diagram of the process of obtaining in-situmeasurements of a process on the substrate.

FIG. 9 shows a flow diagram of an exemplary process that may beimplemented using the system of FIG. 7 ;

FIG. 10A is a transmission electron microscopy (TEM) image showing Sinanostructures manufactured with DIS;

FIG. 10B shows 2-D XPS in-situ spectra showing a thin-film of 10-nm Auon Si for pre-irradiation and post irradiation, with corresponding TEMimages;

FIG. 11 shows a schematic illustration of single layer minors (SLMs) forgas-discharge produced plasma set-ups bombarded by energetic particles(Xe, Sn);

FIG. 12 shows the LEISS spectra for thermal and energetic (e.g.irradiated) Sn on Ru sample cases;

FIG. 13 shows result of surface Sn fraction as a function of fluencewith the relative 13.5-nm reflectivity evolution during exposure of Rhmirror surfaces, as well as relative EUVR in percent loss from theinitial reflectivity; and

FIG. 14 shows two-dimensional (10.times.10 .mu.m) atomic forcemicroscope (AFM) images and roughness values.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of thepresent disclosure, reference will now be made to the embodimentsillustrated in the drawings, and specific language will be used todescribe the same. It will nevertheless be understood that no limitationof the scope of this disclosure is thereby intended.

In at least some embodiments described herein, broad-beam ions combinedwith rastered focused ions and gradient ion-beam profiles are sequencedand/or combined with reactive and/or non-reactive thermal beams thatcontrol the surface topography, chemistry and structure at the micro andnano scale. The technology described in the present disclosureadvantageously benefits from a self-organized arrangement in irradiatedsurfaces dominated by ion-induced erosion and surface diffusion. Thetechnology as described in the present disclosure can transform thesynthesis and design of nano-structured systems by identifying thecomposition-dependent mechanisms that drive self-organization onirradiation-driven micro- and nano-structures enabling tunability andcontrol of their chemical and electronic properties. In particular, thetechnology as described in the present disclosure has importantramifications for biomaterials which is important for introducing noveldesign pathways tuning bioactive properties of thin-film coatings usedin multiple applications for biocompatibility and bio-surface materialadaptability.

The technology as described in the present disclosure includes threeparts: 1) an advanced synthesis process (identified below as directedirradiation synthesis), 2) an advanced tool particular for this processand 3) unique multi-functional micro- and nano-scale structuresgenerated as a result of the processing.

Directed irradiation synthesis (DIS), uniquely couples ion-beam surfaceirradiation and thermal particle exposure to induce complex macro andnano-scale structures that result in enhanced optical, electronic,chemical, biological and/or magnetic properties. One key feature is thatfrom one process step multi-functional micro and/or nano-scalestructures can be synthesized with scalability to high-volumemanufacturing (HVM). This scalability is on par with current top-downtechniques such as focused-charged particle beam lithography that areorders of magnitude short of relevant HVM throughput. Furthermore, thissynthesis approach is on par with typical bottom-up techniques that relyon thermal-chemical reactions from either chemical solutions ornano-imprint technologies. These approaches lack high fidelity controland manipulation of physical properties; for example where only oneproperty can be controlled in a narrow set of synthesis variables (e.g.temperature, chemical potential, etc.). In addition these techniqueshave a limited range of material classes they can modify (e.g. ceramicsvs. polymers vs. metals). The technology described in the presentdisclosure can therefor advantageously provide a scalable, low-cost,modification tool and process that can manufacture multi-functionalmicro- and nano-scale structures on a large class of materials.

The advanced DIS tool, described below in connection with FIG. 7 ,includes coupling of an in-situ surface characterization diagnosticcoupled to process modification sources (e.g. broad-beam, focused-beamand thermal-beam) to allow complete multi-scale (e.g. from nano tomicro) control of properties and function. The micro and nano-scalestructures synthesized by DIS are uniquely characterized by their multifunctional capability (e.g. a region of the material rendered bothmagnetic and biomimetic as well as contain nanophotonic features forsensing).

FIG. 1 shows a schematic of the components used to carry out exemplaryDIS processes according to the invention. As shown in FIG. 1 , at leastone embodiment of a system 100 for carrying out DIS includes a broadbeam ion source (BBIS) 102, a rastered focused ion-beam source (FIBS)104, and a thermal particle source 106. The BBIS 102 is coupled to theFIBS 104 and is matched with the thermal particle source 106. Thethermal particles generated by the thermal particle source can bereactive or non-reactive. For other example processes, the BBIS 102 iscoupled to a plurality of rastered focused ion-beam sources similar tothe FIBS 104 and/or a plurality of thermal particles sources.

It will be appreciated that in the embodiments described herein, theterm focused ion beam or FIBS is not intended to cover items thatproduce ion beams with spot sizes on the order of a few microns, butalso ion beams with spot sizes up to on the order of 0.1-5.0 mm in size.The term focused ion beam is used merely to distinguish the beam andbeam source from those of the broad beam ion source 102.

In accordance with at least some exemplary DIS processes, such as thosediscussed below in connection with FIG. 2 , the flux ratios of eachsource is varied according to energy-material surface interactionmatching that results in balancing the thermal atom composition andion-induced erosion and surface diffusion yielding novel surfacestructuring.

Also shown in FIG. 1 is a substrate 110 having a substrate surface 112.In general, the sources 102, 104 and 106 are configured such that theyall simultaneously operate on the same work area of the substratesurface 112. By way of example, FIG. 3 shows a schematic ofDIS-generated microstructures 302 and smaller microstructures 304 on thesubstrate surface 112 generated by the system 100 of FIG. 1 . TheDIS-derived microstructure 302 and smaller micro-structures 304 have ashape and size varies with space along a 150.times.150 .mu.m view. Thesurface chemistry of each of the structures also varies as a function ofthe particle-beam configuration.

FIG. 2 shows a flow diagram of an exemplary embodiment of a DIS processthat may be carried out by the arrangement of FIG. 1 . In thisembodiment, the DIS process produces microstructures or nanostructureson the substrate surface 112, each of which is a small fraction of thesize of the smallest beam produced by the sources 102, 104, 106. As willbe discussed below, the morphology of the nanostructures andmicrostructures, including the size, shape, and spacing thereof, can becontrolled by altering parameters of one or more the operationalparameters of the sources 102, 104, and 106. Because the beams arelarger than the produced structures, large scale production of surfacesof with multiple micro or nano structures can be accomplished morequickly than using individualized top-down processing, or conventionalbottom-up processing.

In a first step 202, the substrate 110 having the substrate surface 112is provided in a fixture, not shown, where the sources 102, 104 and 106may operate on the substrate 110 and/or substrate surface 112. In anexample, the substrate surface 112 should be relatively smooth, having aroughness of approximately 0.3 to 0.5 nm root-mean-square. To this end,the substrate 110 may suitably be a silicon substrate with an ultra-thinfilm of 40-50 nm precious metal deposited thereon, forming the substratesurface 112. The thin film substrate surface 112 may be formed ofRhodium (Rh), Ruthenium (Ru) or Palladium (Pd).

In a second step 204, a set of control parameters are provided to atleast the FIBS 104 and the thermal source 106. The set of controlparameters corresponds to a desired nanostructure topology. In theexample generating the structures of FIG. 3 , a set of controlparameters are provided to the BBIS 102, as well as the FIBS 104 andthermal source 106. The parameters can include any and all parametersthat affect or define the beams generated by the FIBS 104, thermalsource 106 and the BBIS 102. The parameter control may occur in anautomated fashion, such as under the control of a numerical controldevice or a general purpose or special purpose computer. Each of suchautomation elements, not shown, includes a processing device and amemory containing programming instructions, not shown, which cause theprocessing device to provide the parameters, in conjunction with thestandard control equipment of the beam sources 102, 104 and/or 106. Thememory may also contain a database that associates desired nanostructureor microstructure morphologies with specific corresponding beamparameters.

In this case, the FIBS 104 is configured to provide heavy ions, such asTin (Sn) or Xenon (Xe). The parameters provided to the FIBS 104 thosethat produce a beam 120 at an energy of between 500 and 1000 eV to aspot of about 0.5 mm to 1.0 mm. In one embodiment, the FIBS 104 isconfigured to have an ion-beam profile that decrease its flux 66% overthe full diameter of the beam. As will be discussed below, this allows asingle beam operation to create sets of nanostructures having acontrolled variety of sizes. Decreasing the flux 66% over the fulldiameter allows the morphology of the nanostructures to vary between5-10 .mu.m. Suitable controls sufficient to generate the focused ionbeam sources are conventional and known.

The parameters of the thermal source 106 are those that produce acollimated thermal beam (122) spot of low-wetting material, such as Tin(Sn), which is deposited on the surface of the substrate surface 112.The substrate surface 112 in this example may suitably be a thin film ofRuthenium (Ru). Preferably, the area of deposition is at least ten timesthat of the focused ion beam spot produced by the FIBS 104.

It will be appreciated that the flux of the thermal source 106 is variedwith the flux of the FIBS 104 to proportions or fractions that influencethe shape and spacing the microstructure or nanostructure morphology.For larger structures (e.g. >0.5-1.0 .mu.m size) and larger spacing, thethermal-to-ion flux (TIF) ratio should be below 0.33.

The BBIS 102 is used with light or heavy species depending on thedesired fine-tuning of the surface morphology. A sample light specieswould be Neon, and a sample heavy species would be Xenon. The BBIS 102should produce a beam with a normal incident angle. The energy can varyfrom below 100 eV to about 1000 eV. The structures of FIG. 3 can becreate with 1-keV Xe ions at normal incidence to the surface area.

Once the parameters of the beams are provided to the sources 102, 104,106, step 306 involves forming a plurality of nanostructures ormicrostructures 116 in a first surface area 114 of the substrate 110 byexposing the substrate surface 112 to an ion beam 120 from the FIBS 104ion beam source and thermal energy 122 from the thermal source 106. Inthis embodiment, a broad ion beam 124 as discussed above is alsoapplied. To form exemplary microstructures, the fluence (dose), measuredby the irradiation time multiplied by the ion flux, should beapproximately 10.sup.16-10.sup.17 cm.sup.−2. By increasing the fluence,wider spacing between structures of on the order of 1-10 .mu.m can beachieved.

As discussed above, the ion beam 120 from the FIBS 104 has a first areaof effect or spot size on the substrate surface of 0.5 to 1.0 mm. Thethermal energy 122 has an second area of effect or spot size on thesubstrate of at least ten times the first area of effect of the ion beam120. Naturally, each of the first area and the second area includes thefirst surface area 114 in which the nanostructures and/ormicrostructures 116 are formed. In other words, the coincident beamsunder the set of control parameters produce a plurality of structures.

It will be appreciated that the focused ion-beam 120 is preferably ofnormal incidence to the substrate surface 112 or at angles of no morethan 45 degrees. The thermal beam 122 can be an incident directionbecause the irradiation-induced etching step will remove an unwantedcorrugation (order of 10-50 nm rms roughness) from deposition.

As shown in FIG. 3 , different size structures 302, 304 may be producedacross a gradient if desired. This may be accomplished in a number ofways. Firstly, as discussed above, the flux gradient of the ion beam 120may vary sufficiently to produce structures of different sizes atdifferent areas on the surface 112 without moving the beam. Secondly,two ion beams with different parameters may be used simultaneously—onehaving a first TIF (with respect to the thermal source 106) forproducing the structures 302, and the other having a second, differentTIF (with respect to the thermal source 106) for producing thestructures 304. Finally, the parameters of the FIBS 104 may be alteredas the beam 120 is moved or rastered from a first area producing thestructures 302 to the area producing the structures 304. In such a case,a predetermined sequence of parameters may be used to produce differentstructures in different areas of the substrate surface 112.

Advanced Synthesis Process

Thus, the advanced synthesis process according to the present disclosurein general includes a sequenced combination of broad and focusedion-beams combined with thermal metal and/or reactive atoms (e.g. B, C,N, O and/or F) where their combination yield high-fidelity control ofthe surface chemistry, topology and structure of surfaces and interfacesin either bulk or thin-film configurations. This technology is definedas directed irradiation synthesis (DIS) due to its intrinsic dependenceon irradiation-driven mechanisms (e.g. such as sputtering andion-induced surface diffusion) at the surface 112. This control alsoallows the synthesis of small (e.g. 10-1000 nm) clusters of variousshapes and designs on candidate substrates. The technologyadvantageously makes use of mass-redistribution limited regime wheresurface erosion and diffusion dictate self-organization into micro- andnano-scale structures. The technology also includes carefullycontrolling sequence and beam profile configurations to obtain desiredsurface erosion-dominated mechanisms to control size, shape andcomposition of micro and nano-scale structures. This approach tocombinatorial design space across multiple scales (e.g. atomic to nanoto micro) is one advantageous aspect of DIS. Control parameters includethe ion beam flux to thermal flux ratio variation in sequence incombination with varied energy and incidence of angles. For example, DIScan include three different ion-beams with two focused beams and onebroad-beam with a profile that renders a controlled gradient of the fluxof ions laterally over the surface of the sample. In addition, thetechnology described in the present disclosure can use the energeticions to improve the chemical and mechanical properties of thenanostructured surfaces. Ion implantation has been applied to themodification of metals for improving the wear and corrosion resistance.The ultimate goal for ion implantation in this context can be tosimultaneously influence the biochemistry and biomechanics of candidatecoatings for improving biomedical implants.

To further describe the technology, take for example a case where Snenergetic ions (120) and Sn thermal atoms (122) arrive at a surface 112of a thin-film, in this case ruthenium (Ru). Computational simulationswith generated modeling code shown in FIG. 4 show how by controlling theratio of fluxes between thermal and energetic particles of Sn (i.e.beams 120 and 122 of FIG. 1 ), substantial changes to surfacecomposition and ultimately physical properties are possible.

An example of physical changes driven by compositional changes on thesurface is shown in FIG. 5 (illustrates the conditions for in-situ DISexperiments that demonstrate the capability). Referring to FIG. 5 , aschematic of the DIS synthesis process for energetic, thermal andcombined energetic-thermal metal beams on a transition-metal thin-filmis depicted. The process is not dependent on any of these elements andconsiders the chemical potentials of the incident metal species andsurface free energy of the implanted vs. deposited metal particles andthe substrate (e.g. thin-film) material. Therefore the example describedherein is not intended as limiting, rather its used to illustrate theconcept of combining multiple beams (e.g. in this case a thermal andenergetic metal beam) that depending on their flux ratios and ion-beamprofile can induced spontaneous self-organized patterns on the surfaceof the thin-film. This balance can lead to significant changes insurface composition and surface nanoscale morphology or patterning thatultimately can dramatically change the physical properties of thesystem. In this case the optical reflectivity of the Ru thin-film (canbe also Pd or Rh) is significantly changed in the extreme ultravioletwavelength range.

FIG. 6 shows an example of the in-situ data for DIS-generated surfacepatterns that influence the optical EUV reflectivity of the system.Referring to FIG. 6 , a graph of % initial reflectivity Sn fluence andSn monolayer deposited is provided. The optical 13.5-nm relativereflectivity from thin films of Ru, Rh or Pd vs. the amount ofSn-particle monolayers either implanted (e.g. from energetic Sn ions) ordeposited (e.g. from thermal Sn atoms) on the thin-film surface. Theconcentration of Sn varies on the surface as a function of the g ratioof ion flux to thermal flux. Further detail regarding experimentalresults that provided the data in FIG. 6 is provided below in connectionwith FIGS. 11-14

Advanced Tooling

An improvement to the method of FIG. 2 includes the ability to monitorsome of the changes to the substrate surface 112, which can be used tooptimize and/or enhance certain processes. To this end, FIG. 7 shows aschematic diagram of a unique tool system 700 that includes the elementsof the system 100 of FIG. 1 , but further includes devices and methodsfor monitoring and controlling the process.

More specifically, it is advantageous that the system be ultimately“scalable” both in duty cycle (e.g. high-volume manufacturing) and, moreimportantly, in synthesizing structures from the atomic to nano tomicro-scale. This multi-scale approach and the manipulation ofmechanisms across various time scales is facilitated by the processingsystem 700 of FIG. 7 .

In general, the system 700 includes a collection of ion-beam sources,for example, the sources 102 and 104 of FIG. 1 , a source of thermalatoms (either reactive or non-reactive), for example, the thermal source106 of FIG. 1 , an in-situ diagnosis unit 702 of the modified surfaceand emission plume, and a controller 704. The diagnosis unit 702 allowsfor templates or modified surfaces/interfaces during processing. In-situdiagnosis allows for direct correlation of the surface nanostructures(or microstructures) and surface composition. Based on characteristicsmeasured in in situ by the diagnosis unit, the controller 704 may alterthe parameters of one or more of the beams 102, 104 and 106.

The general processing tool is within a conventional thin-film growthvacuum system 706 with base pressures between 10.sup.−7-10.sup.−8 mbar.The first component as stated earlier includes a series or collection ofion-beam sources 102, 104 juxtaposed to tailor ion flux, incidence anglewith respect to the sample surface and energy. A plurality of FIBS maybe used to achieve different morphologies in different areas of thesubstrate 110, as mentioned above. The surface and energy are importantin dictating the surface morphology along with the thermal atom flux. Aseries of thermal atom sources (e.g. source 106) is used in conjunctionwith ion-beam sources. As discussed above, the flux ratios betweenion-beam sources 102 and thermal atom beam sources 106 are tuneddepending on desired surface morphology and surface composition.

There may be a need for additional ion-beam energy onto a surface andmodulation of the beam profile, which can be accomplished with a focusedion-beam source that is rastered along the irradiated surface plane.

FIG. 9 shows a flow diagram 900 of an exemplary process that may beimplemented using the system 700 of FIG. 7 . Reference is also made toFIG. 8 . FIG. 8 shows a schematic diagram of the process of obtainingin-situ measurements of a process on the substrate.

With reference to FIG. 9 , the process begins with providing thesubstrate 110 having the substrate surface 112 (step 905). Thereafter,in step 910, the method includes generating nanostructures ormicrostructures on the substrate surface 712 at least in part byexposing the substrate surface to thermal particles A from a thermalparticle source (e.g. 106) while irradiating the substrate surface withan ion beam D (e.g. 104).

In step 915, the probe (i.e. diagnosis unit 702) obtains a measurementof a characteristic of the substrate surface 712. The measurement maysuitably be taken from the emitted species B, C (See FIG. 8 ). The probemay suitable probe the surface to generate the emitted species, which iscaptured by a LEISS or other device, to measure the angle, energy and/orflux of the emitted species. One or more of those parameters can provideinformation regarding the surface chemistry and/or other surfacecharacteristics of the substrate 710. Examples of this are discussedbelow in connection with the experimental results and FIGS. 11 to 14 .

In step 920, at least one of the thermal particle source and the ionbeam may be adjusted based on the measurement taken in step 915. Thismay be used to ensure proper processing or to effectuate a sequence ofbeam characteristics based on the evolution of surface characteristics.In the embodiment of FIG. 7 , this step is carried out automatically bythe controller 704 (which includes a processing circuit). However, step920 may be done manually.

A number of examples of multi-functional micro- and nano-scalestructures that demonstrate reduction to practice of directedirradiation synthesis were investigated. We also list a number of DISapplications of the technology to demonstrate the breadth of the use ofthe technology.

DIS Applications for Quantum Dot Nanomanufacturing

While the example discussed further above in connection with FIG. 3shows microstructures 302, 304 generated using DIS techniques, DIStechniques may also be used to manufacture nanometer structures on asubstrate in large scale. For example, structures between 1-10 nm insize are desired from a family of semiconductors that can be used forquantum computing, spintronics and other advanced nanoelectronicdevices. FIG. 10A shows DIS-generated nanoscale Si structures of about1.5-2.0 nm in size manufactured over a 1-cm.sup.2 area in a few seconds.In particular, FIG. 10A is a transmission electron microscopy (TEM)image showing Si nanostructures nanomanufactured with DIS. FIG. 10Bshows 2-D XPS in-situ spectra showing a thin-film of 10-nm Au on Si forpre-irradiation (b1) and post irradiation (b2), with corresponding TEMimages c and d. Irradiation-induced mechanisms lead to the synthesis ofSi nanostructures only on the surface covered by Au.

The spatial scalability is limitless only restricted by the broad-beamion sources, which can effectively irradiate 300-mm conventional waferareas. Thermal and focused-ion beam sources also are scalable and thusthroughput is well in range of today's nanomanufacturing levelsaveraging 150-200 wafers-per-hour (wph). The ultra thin-film synthesiscan be combined with post-deposition combined irradiation and thermalatom deposition to further functionalize the nanomanufactured quantumdots into 3D nanoscale multi-functional structures. The balance betweenerosion and surface diffusion-dominated regimes can precisely controllayered functional structures to yield multi-functional performanceincluding combining nanoelectronic properties with optical propertiesand advanced chemical properties from one structure and onenanomanufacturing step.

DIS Applications for Bone Contact Implants

Biomaterials that are utilized to be definitive or temporally in contactwith bone, are susceptible to be surface improved and properly designedby DIS. Metal, ceramics and polymers parts of joint prosthesis, dentaland crowns implants, as well as osteo-synthesis materials can beproperly surface modified. In case of titanium used for both jointsreplacements and dental implants, DIS is a unique technique to obtainoptimum micro and nano roughness parameters to improve osteoblastsadhesion and proliferation. Micro and nano roughness are optimized foroptimum adhesion of both osteoblasts and proteins, which implies abetter osteointegration of titanium implants. Specifically, vertical andhorizontal roughness parameters are both micro and nano scale can besimultaneously and precisely controlled by DIS, optimizing cellsadhesion and osteointegration in a unique manner.

Ceramics parts used in both joints and dental crowns replacements can bealso improved by DIS technique. Critical properties of these parts fortheir performance, wear resistance and fracture toughness, are clearlyenhanced by nanostructuring of their surfaces: surface confinednanostructure of bioceramics increases surface hardness and fracturetoughness, which are crucial properties for joints and crownsreplacements. Controlled defects at the surface of these bioceramicsallowed the existence of a novel toughening mechanism of nanodefects ornanocracking, which focused at the surface enhancing the fracturetoughness.

Polymers parts of joints replacements frequently suffer wear and debris,which produces bone necrosis and further implant loosening. DIStechnique allows a unique controlled surface hardening of polymersparts, improving their wear resistance. This is achieved by a novel DISeffect to control the polymer crystallinity in an outer layer of thebulk material.

DIS Applications for Increased Hemocompatibility of CardiovascularBiomaterials

Biomaterials in prolonged contact with blood should be surface modifiedin order to avoid activation of different systems of coagulationcascade. Nanostructured and biofunctionalized surfaces obtained by DISensure the blood compatibility of stents, vessel grafts and valvesmaterials used for cardiovascular applications. In other words, surfacesobtained by DIS technique doesn't affect hemostasis equilibrium normallypresent between inner walls of blood vessel and blood itself. Newnanostructured surfaces obtained by DIS ensure that all biomaterials inprolonged contact with blood will not activate the different systems ofcoagulation cascade and further thrombus and formation.

DIS Applications for Enhance Corrosion Resistance of Coatings and BulkMaterials, as Well as for Wear Resistance and Fracture Toughness of HardMaterials

Desired goal of mechanical equilibrium for hard and brittle materialsfor tools is that one between hardness (wear resistance) and fracturetoughness. Nanostructured surfaces on hard and brittle materialscontrolled by DIS technique allow us to get a unique optimum equilibriumbetween hardness and fracture toughness of tools hard materials.Surfaces confined nanostructure enhances surface hardness of tools, aswell as that nanostructure and controlled nanodefects enhance thenecessary energy to propagate natural/processing defects which arepresent within those tools. Nanostructured surfaces by DIS increasecorrosion resistance of metals and ceramics in a novel and drasticmanner. DIS modified surfaces generate a stronger barrier for aggressiveenvironments as well as also increase the corrosion potential of manybulk metals and coatings. Controlled nanostructure and nanodefects ofmetals at an outer layer by DIS, as well as chemical composition,improves defects (dislocations, vacancies, etc.) distribution whichmeans higher corrosion potential due to much lower sensitive to createlocal electrochemical cells between anodic and cathodic areas.

DIS Application for Cell Regrowth in Damaged Areas of the Spinal Cordand Brain

The technology described in the present disclosure has potential impacton the field of regenerative medicine. Recent literature supports thenovel method of using nanotopography to regulate and control cell fate.The technology described in the present disclosure would be able topromote adhesion, migration, and alignment of cell function by alteringtopography structure. In particular this has implications on the nervoussystem. The technology described in the present disclosure can lead toprecise surface topographies that allow neurons coupled with biophysicaland biochemical cues to promote regrowth in damaged areas of the spinalcord and brain.

DIS Application to Promote Broad Range of Device Implantation,Application, and Effectiveness by Minimizing Foreign Body Response (FBR)

The technology described in the present disclosure has potential impacton a broad range of devices including medical/pharmaceuticalapplications. A few examples of specific devices include; biosensors,catheters, and even artificial organs. Many of these types of devicesperform promising in lab settings but fail during clinical applications.It is very costly and difficult to replicate in vitro and in vivoexperiments to mimic the body's unique response to the device. Thedifficulty in replicating preliminary results found in a lab to clinicalstudies factors greatly on the body's unique response to the materialonce implanted. The body naturally reacts via an inflammatory and wouldhealing response following foreign material implantation. Depending onthe extent of the injury in the implantation procedure and the materialsthat make up the actual device FBR can be mild to severe. To minimizeFBR, DIS is able to alter the surface morphology of a device regardlessof its material composition. Through particular surface construction itwill not only help minimize FBR but also promote functionality andlongevity by protecting the material against things like colonizingbacteria. DIS can also accomplish this by not only altering the surface,but also developing a multi-functional nanostructured multilayerthin-film coating to promote targeted cell/tissue growth andregeneration.

Experimental Results

To investigate how reflectivity of 13.5 nm light and chemicalcomposition are affected by irradiation, three separate Rh samplesubstrate surfaces and three separate Ru sample substrate surfaces werebombarded with energetic Xe+ and thermal Sn particles simultaneously asillustrated in FIG. 1 . LEISS and EUV reflectivity in-situcharacterizations were made at specific intervals in the experiment,after 3, 6, 12, 18, 27, and 36 minutes after the start of theexperiment. To correlate these results with the final surface structureof the samples, ex-situ imaging was done at the Radiation Surface andInterface Science Engineering Laboratory at Purdue University using theatomic force microscope (AFM).

Experimental Setup

The multi-beam facility similar to the system 700 of FIG. 7 is equippedwith various in-situ surface characterization techniques (i.e. thediagnostic unit 704), including both electron (Auger, photoelectron) andion scattering spectroscopies, as well as a unique real-time ion-inducedsputtering yield diagnostic based on a dual quartz crystal microbalance(QCM-DCU), capable of measuring deposition rates smaller than 0.1 nm/sby collection of sputtered material. The vacuum system includes tworoughing pumps, an ion pump and a turbo-molecular pump; this vacuumsystem reaches ultimate pressures below 10.sup.−9 bar in a few hours.

FIG. 11 shows an illustration of how the samples, single layer minors(SLMs) for gas-discharge produced plasma set-ups were bombarded byenergetic particles (Xe, Sn), that typically implant in surfaces orsputter them, and exposed to thermal particles (Sn) that will typicallynucleate on surfaces.

To simulate experimental conditions in a real EUV light source device,fast ions equivalent to candidate 13.5-nm radiator fuels are used. Forthe present disclosure, both thermal and energetic Sn were used exposingsamples mostly at room temperature. For delivery of Sn material to thesample, two pieces of equipment are used. Exposure to thermal atoms isdone using a four-pocket electron beam evaporator EGN-4 from OxfordApplied Research with one of the pockets loaded with Sn. The evaporatoris operated upside down using a special crucible installed withpre-wetted Sn. The evaporator is calibrated two ways. First, theevaporator is tested in a separate test chamber using a single quartzcrystal microbalance (QCM). The deposition rate of Sn is measured for agiven current of Sn particles. Current monitors near the exit of thepocket measure an ion current proportional to the evaporative flux by aconstant factor, which is material dependent. To confine the depositionof Sn to the sample (SLM), a nozzle was designed and constructed tolimit the flux, such that the deposition was confined to the samplearea. After the addition of the cone, the evaporated material isconfined to the sample and the deposition spot has a size of about 5 mmin diameter centered on the sample. Based on the calibration with thesingle QCM, the deposition rate is 0.016 nm min.sub.−1 nA.sub.−1.Multiplying this value by the ion current measured by the flux monitorgives the deposition rate in nm/min. The second method of calibration isconducted in-situ utilizing the rotating quartz crystalmicrobalance—dual crystal unit (QCM-DCU). In this case the QCM-DCU isrotated to the sample position and the EGN-4 calibrated at various powerlevels. The first calibration method is necessary in case unexpectedpower levels are obtained, thus requiring a vent and check of theevaporator. In this manner, only the side vacuum chamber is vented.Typical Sn deposition rates used for most studies presented weremeasured to be about 0.2 nm/min, depending on the particular experimentconducted.

For delivery of energetic Sn flux, a metal ion source currently operatedwith Sn is used. A slug of Sn is heated inside the gun ionizer, andmetal ions are generated. These ions are transported to the exit of thegun by a set of electrostatic lenses, which can be controlled to modifythe beam current and size. The exit of the source is equipped with anoctupole lens system, which rasters the Sn-ion beam in two directions.In addition to the optical column, the source is also equipped with a3.degree. bend Wein filter, which only allows particles with aparticular mass to charge ratio to exit the gun. The selection of themass or charge state of the ion is done by varying the current on thefilter's electromagnet. The source can produce an ion beam with up to 50nA of current and a 1 to 2 mm spot diameter resulting in ion fluxes inthe range 10.sup.10-10.sup.12 ions cm.sup.−2. The sample holder includesan UHV heater that can heat the sample to temperatures near 500 C. Inaddition, studies of ion-surface interaction can be done either atnormal incidence with respect to the minor sample surface normal or atoblique incidence using a rotating manipulator with resolution of about0.5 degrees rotation.

Characterization is conducted in-situ using low-energy ion scatteringspectroscopy (LEISS). In other words, the diagnosis unit 702 of FIG. 7may suitably include a LEISS. FIG. 12 shows the LEISS spectra forthermal and energetic (e.g. irradiated) Sn on Ru sample cases. Thecross-section for elastic scattering collisions is similar in magnitudebetween the incident ion, He, and samples surfaces that include: Rh, Rhand Sn. The peaks associated with Sn and the underlying thin-filmsurface (e.g. Rh vs Ru) are largest for Sn atom deposition. This isconsistent with a sputter-induced mechanism, which maintains a partialSn fraction on the samples with irradiated Sn.

Results and Analysis

Simultaneous Irradiation with Xe and Deposition with Sn Particles FIG.13 shows result of surface Sn fraction as a function of fluence with therelative 13.5-nm reflectivity evolution during exposure of Rh minorsurfaces. FIG. 13 also shows relative EUVR in percent loss from theinitial reflectivity.

Relative reflectivity of Rh-318 and Rh-319 decreased by 41.6% and 48.5%,respectively, after 36 minutes. Rh-320 had a higher energetic particlefluence, but relative reflectivity was phenomenally well maintained,with a loss of only 18.3%. While reflectivity of Rh-318 and Rh-319decreased as the experiment progressed, Rh-320 had a local maximum atapproximately 2.21.times.1016 Sn cm.sup.−2 where reflectivity increasedto 94.7%. The corresponding Xe+ fluence, 2.25.times.1016 Xe+ cm.sup.−2,exceeds the final fluences for the other two samples. This suggests thatRh-320 reached a threshold—too high for the other samples—where thesurface changed such that reflectivity could reach a maximum. Whetherthis threshold is related to fluence of one debris type (thermal orenergetic particles), the ratio between the Xe+ and Sn particlefluences, flux (rate of deposition or irradiation), or something else,cannot be determined from the data in the present disclosure.

LEISS measurements gave the surface fraction of Sn, which for Rh-318 andRh-319 already at the first measurement after 3 minutes of exposure, was1 (fully covered). The corresponding EUV reflectivity measurements were91.1 and 90.1%, which then decreased as more Sn was deposited. As the Sncoating grows thicker, the incoming photons would switch frominteracting with shallow Rh atoms to interacting more with the lessreflective Sn atoms. Since a full layer of Sn covered Rh-318 and Rh-319throughout the experiment, it would suggest that this transition ofphoton interaction took place but cannot be verified since Sn layerthicknesses were not measured. For Rh-320 the surface fraction of Sn isinitially around 0.7, then at a Sn fluence of 2.21.times.1016 cm.sup.−2the fraction drops to 0.485: this drop corresponds to the maximum in EUVreflectivity. Close examination of the data points FIG. 6 reveal that asthe Sn fraction increases, corresponding reflectivity decreases. Thisnegative correlation indicates that elemental composition of the surfacehas a direct effect on EUV reflectivity, and that Sn specifically isdetrimental as compared to Rh.

The AFM investigated the morphology of the samples. Analysis softwarefrom the AFM supplier was used to calculate surface roughness: area Ra,area RMS (root mean square), average height, and maximum height. Table 1illustrates the results. Three regions were identified for exposure ofsamples. These regions were modified according to the ion flux to atomflux ratio levels across the surface of the sample. Region 1 has thehighest ion flux down to Region 3 with the least amount. Region 1, avery small region located at the center of region 2, for Rh-319 andRh-320 seemed almost sputtered clean because of the energetic LEISSbeam, although the Ne+ flux was low. The scan of region 1 for Rh-318shows peculiarly strong growth, and in fact, despite efforts to aim theLEISS beam dead center, region 1 may not have been where it was expectedit to be. Region 2 was targeted by the EUV beam (diameter 3-5 mm) and istherefore expected to have the strongest effect on reflectivity. Region3 should not have any effect since the region lies outside of the areawhere reflectivity measurements were taken. Region 3 would, however,affect LEISS scans. According to the region 3 images of Rh-318 andRh-319, irregularities fill the entire view. According to FIG. 6 , Sncovers their whole surfaces. Region 3 for sample Rh-320 looks lessdense, and this correlates with the Sn surface fraction being lessthan 1. The Sn surface fraction for Rh-318 and Rh-319 was 1 throughoutthe experiment. Region 2, which has a greater effect on LEISS thanregion 3, looks as if it contains islands. Therefore, it can beextrapolated that the space between islands is covered in Sn. Thesurface of Rh-320 is not entirely covered in Sn, since more of thesurface and Sn impurities are sputtered away by the high Xe+ fluence.Exposed Rh, probably in the spaces between islands, is detected by LEISSand contributes to the stable EUV reflectivity of the sample compared toRh-318 and Rh-319.

Region 3 shows more intense growth than region 2 for all samples.Roughness analyses for Rh-318 and Rh-319 reveal that region 2 containsstructures that may look more spaced out that region 3, but the area isrougher (the spacing is represented by average being lower than region3, but maximum height is much higher). Rh-318 has a higher RMS thanRh-319, but better reflectivity (although with errors, thereflectivities are incredibly close). While roughness has an effect onEUV reflectivity, so has centers of absorption: the number of islands orareas that will absorb 13.5-nm light (like Sn) rather than reflect it(like Rh). Assuming that islands are purely Sn, and hence effectivecenters of absorption, Rh-319 has more of them and therefore absorbsmore 13.5-nm light than Rh-318.

For Rh-320 region 2 is smoother than region 3 because the structures aresmaller. This correlates with reflectivity measurements and it can beconcluded that a rougher surface is less reflective. As the structuresbecome smaller (occupy less area, smaller height), relative to thewavelength of the light, the surface will “look” uniform to the lightbecause it cannot resolve the structures as well. This is seen in Rh-318and Rh-319, where the RMS and average height exceed 13.5 nm, whereas forRh-320 they are smaller.

FIG. 14 shows two-dimensional (10.times.10 .mu.m) atomic forcemicroscope (AFM) images and roughness values calculated with the AFMcomputer analysis program.

It will be appreciated that at least some advantages of one or moreembodiments described herein is that structures much smaller than theincident beams (e.g. beams 102, 104, 106) may be created, therebyallowing potentially for larger scale manufacturing of devices. One ormore of the beams (e.g. the FIBS 104) may be rastered (with parametervariation) to generate micro or nano structures having varyingtopologies on the same substrate.

Those skilled in the art will recognize that numerous modifications canbe made to the specific implementations described above. Toimplementations should not be limited to the particular limitationsdescribed. Other limitations may be possible.

What is claimed is:
 1. A method for fabricating structures on asubstrate, comprising: a) providing a substrate having a substratesurface; b) generating nanostructures or microstructures on thesubstrate surface at least in part by exposing the substrate surface tothermal particles from a thermal particle source while irradiating thesubstrate surface with an ion beam, wherein each of the generatednanostructures or microstructures has a smaller surface area defined atthe substrate surface than an area of incidence on the substrate surfaceof the ion beam or a beam generated by the thermal particle source, andwherein at least some of the generated nanostructures or microstructureshave a size that corresponds to a ratio of a flux of the thermalparticle source to a flux of the ion beam; c) after the generating step,obtaining a measurement of a characteristic of the substrate surface;and d) adjusting at least one of the thermal particle source and the ionbeam based on the measurement and exposing the substrate surface to thethermal particles of the thermal particle source while irradiating thesubstrate surface with the ion beam after said adjusting.
 2. The methodof claim 1, wherein step c) further comprises obtaining at least onecharacteristic of an emitted species generated in step b).
 3. The methodof claim 2, wherein the at least one characteristic comprises anemission angle of the emitted species.
 4. The method of claim 2, whereinthe at least one characteristic comprises an energy value.
 5. The methodof claim 2, wherein the at least one characteristic comprises a fluxvalue.
 6. The method of claim 1, wherein step c) includes employing aprobe to obtain a surface characteristic of the substrate surface. 7.The method of claim 6, wherein the surface characteristic comprises atleast one of the group consisting of a chemical property, an electronicproperty and an optical property.
 8. A method for fabricating structureson a substrate, comprising: a) providing a substrate having a substratesurface; b) generating nanostructures or microstructures on thesubstrate surface at least in part by exposing the substrate surface tothermal particles from a thermal particle source while irradiating thesubstrate surface with an ion beam, wherein each of the generatednanostructures or microstructures has a smaller surface area defined atthe substrate surface than an area of incidence on the substrate surfaceof the ion beam or a beam generated by the thermal particle source; c)obtaining a measurement of a characteristic of the substrate surface;and d) adjusting at least one of the thermal particle source and the ionbeam based on the measurement, wherein step b) further comprisesgenerating the nanostructures or microstructures by inducing spontaneousself-organized patterns on the substrate surface.
 9. The method of claim8, wherein step c) further comprises obtaining at least onecharacteristic of an emitted species generated in step b).
 10. Themethod of claim 9, wherein the at least one characteristic comprises anemission angle of the emitted species.
 11. The method of claim 9,wherein the at least one characteristic comprises an energy value. 12.The method of claim 9, wherein the at least one characteristic comprisesa flux value.
 13. The method of claim 8, wherein step c) includesemploying a probe to obtain a surface characteristic of the substratesurface.
 14. The method of claim 13, wherein the surface characteristiccomprises at least one of the group consisting of a chemical property,an electronic property and an optical property.
 15. A method forfabricating structures on a substrate, comprising: a) providing asubstrate having a substrate surface; b) generating nanostructures ormicrostructures on the substrate surface at least in part by exposingthe substrate surface to thermal particles from a thermal particlesource while irradiating the substrate surface with an ion beam, whereineach of the generated nanostructures or microstructures has a smallersurface area defined at the substrate surface than an area of incidenceon the substrate surface of the ion beam or a beam generated by thethermal particle source; c) after the generating step, obtaining ameasurement of a characteristic of the substrate surface; and d)adjusting at least one of the thermal particle source and the ion beambased on the measurement to effectuate a sequence of beamcharacteristics based on an evolution of the characteristics of thesubstrate surface.
 16. The method of claim 15, wherein step c) furthercomprises obtaining at least one characteristic of an emitted speciesgenerated in step b).
 17. The method of claim 16, wherein the at leastone characteristic comprises an emission angle of the emitted species.18. The method of claim 16, wherein the at least one characteristiccomprises an energy value.